Are you asking for a technical or a legal answer? I don't know the rules specifically, but Joe sez an adapter is legal. So, your legal answer is as Joe sez: use an adapter.
From a technical standpoint, the fact that the studs overlap are of no relevance; that an easy exercise. First, does someone make a bolt-on adapter? If so, there's your answer. No need to reinvent the wheel.
If no one makes an adapter, then you're going to have to fabricate one. Off the top of my head, you'll design it out of aluminum, and about as thick as the head of a Allen head cap screw plus enough material for strength (oh, call it 1.8"). You bore a hole out of this plate to match your carb, and taper it nicely to fit your manifold. To secure it to the manifold you'll remove the manifold studs and counterbore the aluminum plate for Allen head cap screws, which will descend below the top of the plate. To secure the carb you'll drill and tap holes in the appropriate place for studs (you can use the same old ones if you want...)
So, find out what's legal, find out if someon has something already, and if not find someone with engineering abilities to design and fab one for you. - GA